Surface model for field emission processes

The processes of field electron emission from solids and field ion production at surfaces are well understood for plane emitting surfaces. The actual surfaces are not plane on an atomic scale and it is worthwhile to develop a way to treat deviations from a flat surface quantitatively, at least to some extent. In this paper the model of a hemispherical projection on a plane surface is set up, as an approximation to the way that an atom projects from the background of a crystalline surface. It is expected that the model will be valuable in analyzing various field emission processes. Application is made to the resolving power of the field ion microscope.